The chalcedony bead is a variety of quartz crystal. Since 1700, it was thought that semi-precious chalcedony stone nuggets personified the control to expel evil spirits as well as, nightmares. Chalcedony beads were most conceded by sailors to shield some individual against drowning.
Astrologers form the middle Ages used to engraved signet rings of chalcedony nugget stones as talismans. Most of their magical stone are made of chalcedony semi-precious stones, especially for Burmese tribes in order for them to protect the house and to keep these stones from eating the people.